/***
 * Copyright 2002-2010 jamod development team
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 * Original implementation by jamod development team.
 * This file modified by Charles Hache <chache@brood.ca>
 ***/

package net.wimpi.modbus.util;

import java.util.Vector;

/**
 * A cleanroom implementation of the Observable pattern.
 * <p/>
 * 
 * @author Dieter Wimberger (wimpi)
 * @version @version@ (@date@)
 */
public class Observable {

	private Vector<Observer> m_Observers;

	/**
	 * Constructs a new Observable instance.
	 */
	public Observable() {
		m_Observers = new Vector<Observer>(10);
	}// constructor

	public int getObserverCount() {
		synchronized (m_Observers) {
			return m_Observers.size();
		}
	}// getObserverCount

	/**
	 * Adds an observer instance if it is not already in the set of observers
	 * for this <tt>Observable</tt>.
	 * 
	 * @param o
	 *            an observer instance to be added.
	 */
	public void addObserver(Observer o) {
		synchronized (m_Observers) {
			if (!m_Observers.contains(o)) {
				m_Observers.addElement(o);

			}
		}
	}// addObserver

	/**
	 * Removes an observer instance from the set of observers of this
	 * <tt>Observable</tt>.
	 * 
	 * @param o
	 *            an observer instance to be removed.
	 */
	public void removeObserver(Observer o) {
		synchronized (m_Observers) {
			m_Observers.removeElement(o);
		}
	}// removeObserver

	/**
	 * Removes all observer instances from the set of observers of this
	 * <tt>Observable</tt>.
	 */
	public void removeObservers() {
		synchronized (m_Observers) {
			m_Observers.removeAllElements();
		}
	}// removeObservers

	/**
	 * Notifies all observer instances in the set of observers of this
	 * <tt>Observable</tt>.
	 * 
	 * @param arg
	 *            an arbitrary argument to be passed.
	 */
	public void notifyObservers(Object arg) {
		synchronized (m_Observers) {
			for (int i = 0; i < m_Observers.size(); i++) {
				((Observer) m_Observers.elementAt(i)).update(this, arg);
			}
		}
	}// notifyObservers

}// class Observable
